Allow usernames and groupnames of length 1

Fixes #204

src/test/groups-test.js

@@ -54,7 +54,7 @@ describe('Groups', function () {
     after(cleanup);
 
     it('cannot create group - too small', function (done) {
-        groups.create('a', function (error) {
+        groups.create('', function (error) {
             expect(error.reason).to.be(GroupError.BAD_FIELD);
             done();
         });

src/test/user-test.js

@@ -162,7 +162,7 @@ describe('User', function () {
         });
 
         it('fails due to short username', function (done) {
-            user.create('Z', PASSWORD, EMAIL, DISPLAY_NAME, AUDIT_SOURCE, function (error, result) {
+            user.create('', PASSWORD, EMAIL, DISPLAY_NAME, AUDIT_SOURCE, function (error, result) {
                 expect(error).to.be.ok();
                 expect(result).to.not.be.ok();
                 expect(error.reason).to.equal(UserError.BAD_FIELD);